The present invention relates to absorbent articles such as diapers, incontinent briefs, training pants, and the like, and more particularly, to absorbent articles having an extensible waist feature providing dynamic fit about the wearer as well as improved containment characteristics of the absorbent article.
Infants and other incontinent individuals wear absorbent articles such as diapers to receive and contain urine and other body exudates. Absorbent articles function both to contain the discharged materials and to isolate these materials from the body of the wearer and from the wearer""s garments and bed clothing. Disposable absorbent articles having many different basic designs are known to the art. For example, U.S. Pat. Re. No. 26,152, entitled xe2x80x9cDisposable Diaperxe2x80x9d issued to Duncan and Baker on Jan. 31, 1967, describes a disposable diaper which has achieved wide acceptance and commercial success. U.S. Pat. No. 3,860,003, entitled xe2x80x9cContractable Side Portions For Disposable Diaperxe2x80x9d, issued to Buell on Jan. 14, 1975, describes an elasticized leg cuff disposable diaper which has achieved wide acceptance and commercial success.
However, absorbent articles have a tendency to sag or gap away from and to slide/slip down on the body of the wearer during wear. This sagging/gapping and sliding/slipping is caused by the relative motions of the wearer as the wearer breathes, moves and changes positions, by the downward forces generated when the absorbent article is loaded with body exudates, and by the rib-like element of the materials of the absorbent article itself when subjected to such wearer""s motions. This sagging/gapping and sliding/slipping of the absorbent article can lead to premature leakage and poor fit of the absorbent article about the wearer in the waist regions and the leg regions of the absorbent article.
In order to more snugly fit absorbent articles about the wearer, certain commercially available absorbent articles have been provided with elastic features. An example of a disposable diaper with elastic side panels is disclosed in U.S. Pat. No. 5,151,092, entitled xe2x80x9cAbsorbent Article With Dynamic Elastic Waist Feature Having Predisposed Flexural Hingexe2x80x9d issued to Buell, Clear, and Falcone on Sep. 22, 1992. However, elastics are costly and require a certain degree of manipulation and handling during assembly. Further, while elastics do provide a degree of stretch for the absorbent article, the components of the absorbent article to which the elastics are attached are typically not elastic such that the elastics must be prestretched prior to being secured to the absorbent article or the inelastic components must be subjected to mechanical stretching (e.g., ring rolling) to enable the added elastic to be effective. Otherwise, the added elastic is restrained by the inelastic components.
Therefore, it is an object of the present invention to provide a relatively low cost, easy to manufacture, absorbent article having sustained dynamic fit about the wearer during use.
It is a further object of the present invention to provide an absorbent article having a unique extensible waist feature, preferably without the use of elastic, that provides sustained dynamic fit and improved resistance to leakage during use due to the conformability of the materials forming the waist feature by virtue of their readily extensible nature.
It is a still further object of the present invention to provide an extensible waist feature on an absorbent article that exhibits an xe2x80x9celastic-likexe2x80x9d behavior in the direction of applied force or elongation without the use of additional elastic material.
It is an even further object of the present invention to provide an extensible back waist feature on an absorbent article that enhances fit and containment by providing multiple zones or panels having different force/extension properties to better distribute the forces encountered by the back waist feature during use and provide the necessary stretch and extension characteristics in those zones.
These and other objects of the present invention will be more readily apparent when considered in reference to the following description and when taken in conjunction with the accompanying drawings.
The present invention provides absorbent articles such as disposable diapers, incontinent briefs, diaper holders, training pants, feminine hygiene garments and the like, that have an extensible back waist feature that improves the dynamic fit as well as the containment characteristics of the absorbent article. Such absorbent articles comprise a chassis assembly preferably comprising a liquid pervious topsheet, a liquid impervious backsheet, and an absorbent core positioned between the topsheet and the backsheet; an extensible back waist feature having multiple panels or zones; and a closure system for maintaining the absorbent article on the wearer.
In a preferred embodiment of the present invention, the absorbent article has a T-shape comprising a chassis assembly and a extensible back waist feature disposed in the back waist region. The extensible back waist feature provides an extensible member that provides a more comfortable and contouring fit by initially conformably fitting the diaper to the wearer and by sustaining this fit. The extensible back waist feature further develops and maintains wearing forces (tensions) that enhance the tensions developed and maintained by the closure system. The extensible back waist feature further provides more effective application of the diaper. The extensible back waist feature has a central waistband panel, a pair of side panels, and a hip panel. Each of the panels are designed to provide different force and extension properties to optimize the fit of the diaper. While each panel of the extensible back waist feature may be constructed from a number of extensible materials, they preferably each comprise a structural elastic-like film (SELF) web since a SELF web allows the force/extension characteristics to be specifically designed for each panel and with a minimum amount of materials (no conventional elastic materials need to be used).
A structural elastic-like film (SELF) web exhibits an elastic-like behavior in the direction of elongation without the use of added elastic materials. SELF webs exhibit at least two significantly different stages of controlled resistive force to elongation along at least one predetermined axis when subjected to an applied elongation in a direction parallel to the predetermined axis. SELF webs include a strainable network having at least two contiguous, distinct, and dissimilar regions. One of the regions is configured so that it will exhibit resistive forces in response to the applied axial elongation in a direction parallel to the predetermined axis before a substantial portion of the other region develops significant resistive forces to the applied elongation. At least one of the regions has a surface-pathlength which is greater than that of the other region as measured substantially parallel to the predetermined axis while the material is in an untensioned condition. The region exhibiting the longer surface-pathlength includes one or more rib-like elements which extend beyond the plane of the other region. SELF webs exhibit first resistive forces to the applied elongation until the elongation of the web is sufficient to cause a substantial portion of the region having the longer surface-pathlength to enter the plane of applied elongation, whereupon the SELF web exhibits second resistive forces to further elongation. The total resistive forces to elongation are higher than the first resistive forces to elongation provided by the first region.